1. Field of the Invention
The present invention is related to a display apparatus of magnetic flux density, especially designed to visualize in a real time the change of magnetic flux density.
2. Description of the Related Art
Any machinery or structure can be effectively used for an extended using time while its safety is guaranteed with sufficient reliability and within the allowed economic efficiency. For this, a nondestructive testing technology, i.e., the quality management to eliminate the goods out-of-specifications in each manufacturing processes, the quality control of materials, the repair inspections to check the occurrence of dangerous defects which the goods are being used by customers is specially important. Among them, the magnetic method using magnetic phenomena and the eddy current method are effective to detect cracks on the surface and near the surface of materials. However, an automatic scanning system must be used to quantitatively measure the distribution of magnetic flux density.
Also, it is necessary to get an enough lift-off to measure the magnetic flux density under the high-temperature conditions or contaminated environments, which becomes the reason for low sensitivity of sensors and, it is also necessary to measure the magnetic flux density with limited sensing areas for large scaled objects.
On the other hand, metal detection doors are usually used to prohibit people from carrying in arms at airports and at places where securities are required. Since the conventional metal detection doors can only check the existence of metallic objects in a limited region, it is difficult to discern hand-held phones, keys, and coins from the arms. Therefore, to visualize the shapes of metallic objects, it is necessary to use X-ray equipment, the metal detection doors and metal detectors at the same time that accompanies burdens in time and cost.
To detect mines or metals buried or imbedded under the ground or on the wall, the metal detection equipment by electromagnetic method is usually used. It is necessary to visualize the distribution or data of magnetic flux density in a large area quantitatively and in a fast manner to discern magnetic particles in the sand, metallic debris, coins and mines.
However, in many cases, the lift-off of sensors from the mines or metals is large enough so that the sensitivity of magnetic sensors is degraded, moreover, it is necessary to measure large area because the area to be measured becomes large with increasing of lift-off.
As described above, in applying the electromagnetic methods to nondestructive tests, metal detection doors and metal detectors, there is no such an apparatus that reduces the effect of lift-off, does not require any space-limited automatic scanning systems, but visualizes the distributed magnetic flux density over a large area quantitatively in a fast manner by using magnetic field sensors with limited area.
Even there is a method using a ferromagnetic flat panel to focus magnetic flux to measure magnetic flux density with high sensitivity, it is necessary to solve the problem of residual magnetization or magnetic hysterises phenomenon in a ferromagnetic flat panel.
In addition to those, it is difficult to manufacture three-dimensional shape of metal because of mechanical characteristics of metals, it is necessary to demagnetizing, and it is not easy to reuse for another shape.
To solve the above-described problems, it is an object of the present invention to provide a display apparatus of magnetic flux density that visualizes and measures the distribution of magnetic flux density over a large area quantitatively in a real time with small spatial limitation.
To achieve the above object, there is provided a display apparatus of magnetic flux density for detecting an internal crack of a metal or a shape of the metal comprising a three-dimensional magnetic flux focusing unit installed near the metal, for concentrating magnetic flux generated by the metal, a magnetic flux density measurement unit installed near the magnetic flux focusing unit, for measuring changes in magnetic flux density concentrated by the magnetic flux focusing unit, and a display unit electrically connected with the magnetic flux measurement unit, for real-time displaying and storing changes in the magnetic flux density.
It is preferred in the present invention that the magnetic flux focusing unit comprise a container having magnetic fluid.
It is preferred in the present invention that the magnetic flux focusing unit comprises a ferromagnetic material.
It is preferred in the present invention that the magnetic flux focusing unit comprises an absorber of magnetic fluid.
It is preferred in the present invention that the absorber is either one of paper or sponge.
It is preferred in the present invention that the outer shape of the magnetic flux focusing unit is one of circle, rectangle or polygon.
It is preferred in the present invention that the magnetic flux focusing unit has the outer shape of the combination of circle, rectangle, or polygon.
It is preferred in the present invention that the magnetic sensor is a Hall sensor comprising a plurality of Hall effect semiconductor chips.
It is preferred in the present invention that the Hall sensor comprises an insulator on which the chips are arranged to a predetermined distance.
It is preferred in the present invention that the display apparatus of magnetic flux density comprises an additional magnetic field generator to magnetize the magnetic materials set up near the magnetic materials.
It is preferred in the present invention that the magnetic field generator comprise a conductor for generating a magnetic field when a current flows.
It is preferred in the present invention that the magnetic field generates is set up on the security door, and the door can detect whether the people walking through it has the magnetic materials or not if the magnetic lens and the magnetic flux density measurement device are set up on one side of the door.
It is preferred in the present invention that the metal is a line patterned on the printed circuit board, magnetic fields are generated around the printed circuit board when currents flow through the lines, and the display device can display the currents flowing through the lines.
It is preferred in the present invention that the meal is buried under the ground and the metal is magnetized by the terrestrial magnetism.